RE: Oxyhemoglobin correction?
Coincidently I was reviewing our amniotic fluid bilirubin method earlier
this week and I noticed an un-referenced statement in an appendix that:
When oxyhemoglobin is present, then 5% of the OD415 can be substracted
from the OD450 to produced a corrected OD450 result.
Michael was the first to mention use of this correction for
oxyhemoglobin inteference in this discussion. Our current amniotic
fluid bilirubin method also measures oxyhemoglobin at OD415,and we
monitor that wavelength for potential interference but do not routinely
correct OD450 the results with the factor.
I am considering implementing the oxyhemoglobin correction factor.
I suppose I could test the validity of the 5% of OD415 factor easily
enough.... but could someone direct me to a publication that describes
an evaluation of the correction factor?
I am concerned that light scattering particulates in turbid samples
(that do not centrifuge down) may lead to a falsely increased
"correction factor" and subsequently lower OD450 results.
regards, Andrew
Andrew Lyon
Calgary, AB.
[log in to unmask] wrote:
>
> We report OD450 corrected for oxyhaemoglobin and a calculated bilirubin.
> Some years ago we stopped using the graph of Liley due to the limited range
> ( I think it started at 20 something weeks to 40 weeks) - transplacental
> transfusions can be performed from about 18 weeks and the data published by
> Queenan et al. Am J Obstet Gynecol 1993:168; 1370-6 is more up to date
> (1993 vs 1961). The test is done is exactly the same way as before but is
> plotted on a different graph.
>
> Michael Freemantle
> Biochemistry Dept
> Sullivan Nicolaides Pathology
> Taringa Ph 07 3377-8638 Fax 07 3870-5989
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